1. Field of the Invention
This invention relates in general to charge injection imaging devices (see U.S. Pat. No. 3,786,263) and more particularly to apparatus for reading out the information stored by such a device.
2. Description Relative to the Prior Art
Current thinking with respect to the readout of a charge injection device (CID) is to employ any of a number of techniques for sensing capacitance changes of the charge-collecting image sites or pixels. Techniques for sensing such capacitance changes have appeared in the literature, although on such technique is described below for purposes of facilitating understanding of the invention.
Two problems are associated with capacitance readout techniques: (1) capacitance differences from pixel to pixel, which may result from any of a number of structural sources within a CID, manifest themselves as pattern noise in the device output and (2) under certain illumination conditions, the visual image corresponding to the output of the CID is distorted intensity-wise. Although the first of the above-noted problems is relatively easy to appreciate, why the second problem should occur is another matter: An analysis is presented below to explain the source of the second problem.